Toyota Motor Corp., which last year overtook General Motors Co. to become the world’s largest automaker even as its profit margins lagged behind the industry, is riding a weakening yen that has Detroit executives concerned.

With Toyota Motor Corp. back on top as the world’s largest automaker, President Akio Toyoda isn’t looking to a relative youngster like the Prius hybrid to defend that lead. Instead, he’s counting on a middle-aged veteran: the 47-year-old Corolla.

Japan’s Nikkei 225 Stock Average fell 11.80, or 0.1 percent, to 9,642.12 as of the 3 p.m. close in Tokyo. The following were among the most active shares in the Japanese market today. Stock symbols are in parentheses after company names.

Most Japanese stocks fell, led by banks and brokerages, as the Wall Street Journal said the scale of U.S. Federal Reserve asset purchases may be less than anticipated. Exporters gained as the yen weakened.

Many people of a certain age remember Mazda Motor Corp.’s catchy ads from the 1970s. “Piston engines go boing-boing,” they said. “Mazda goes hummmm.” The voiceover sang: “There’s nothing like it on the road today; the rotary engine is here to stay.”

Carlos Ghosn, poised to make Nissan Motor Co. into Japan’s most profitable automaker for the first time since at least 1992, is returning to the type of bold pronouncement he was known for a decade ago.